login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A175629
Legendre symbol (n,7).
15
0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1
OFFSET
0,1
COMMENTS
This represents a non-principal Dirichlet character modulo 7.
REFERENCES
T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1986, page 139, k=7, Chi_2(n).
FORMULA
a(n) = a(n+7).
|a(n)| = A109720(n).
a(n) = -a(n-1) - a(n-2) - a(n-3) - a(n-4) - a(n-5) - a(n-6).
G.f.: x*(1 + 2*x + x^2 + 2*x^3 + x^4)/(1 + x + x^2 + x^3 + x^4 + x^5 + x^6).
a(n) == n^3 (mod 7). - Jianing Song, Jun 29 2018
MAPLE
A := proc(n) numtheory[jacobi](n, 7) ; end proc: seq(A(n), n=0..120) ;
MATHEMATICA
LinearRecurrence[{-1, -1, -1, -1, -1, -1}, {0, 1, 1, -1, 1, -1}, 100] (* or *) PadRight[ {}, 100, {0, 1, 1, -1, 1, -1, -1}] (* Harvey P. Dale, Aug 02 2013 *)
Table[JacobiSymbol[n, 7], {n, 0, 100}] (* Vincenzo Librandi, Jun 30 2018 *)
PROG
(Magma) &cat [[0, 1, 1, -1, 1, -1, -1]^^20]; // Vincenzo Librandi, Jun 30 2018
(PARI) a(n) = kronecker(n, 7); \\ Michel Marcus, Jan 28 2019
CROSSREFS
The Legendre symbols (n,p): A091337 (p = 2, Kronecker symbol), A102283 (p = 3), A080891 (p = 5), this sequence (p = 7), A011582 (p = 11), A011583 (p = 13), ..., A011631 (p = 251), A165573 (p = 257), A165574 (p = 263). Also, many other sequences for p > 263 are in the OEIS.
Moebius transform of A035182.
Sequence in context: A101040 A341591 A306453 * A109720 A022932 A334812
KEYWORD
easy,mult,sign
AUTHOR
R. J. Mathar, Jul 29 2010
STATUS
approved